No abstract

Intrarenal blood flow regulation probably affects long-term blood pressure homeostasis. We have previously shown that 5 Hz renal sympathetic stimulation inhibits a humoral renal depressor mechanism, otherwise activated when increasing perfusion pressure to an isolated kidney in a cross-circulation set-up. This inhibition was suggested to occur as a result of a reduction of renomedullary blood flow. Little is known about nervous blood flow regulation within the medulla. Therefore in this study, total renal (RBF), cortical (CBF) and papillary (PBF) blood flows were separately measured by ultrasonic and laser-Doppler techniques in Wistar rats during graded renal sympathetic stimulations. Periods of 15 min stimulation at 0.5, 2 and 5 Hz were performed in random order. RBF decreased at 0.5 Hz by 1%, at 2 Hz by 16% (P < 0.001) and at 5 Hz by 49% (P < 0.001). In a similar fashion (r = 0.73, P < 0.001), CBF decreased by 1%, 10% (P < 0.001) and 37% (P < 0.001), respectively. By contrast, PBF increased by 2% at 0.5 Hz and 4% at 2 Hz, while it decreased at 5 Hz, by 4% (P < 0.05, compared with 2 Hz). It seems therefore, that superficial renocortical and total renal blood flows are closely regulated by renal sympathetic nerves with increasing vasoconstriction at higher frequencies, while medullary blood flow, on the other hand, seems to be under strong local control, tending to offset neurogenic flow restrictions.

IMPORTANCE Modern data regarding incidence and modes of death of patients with aortic stenosis (AS) are restricted to tertiary centers or studies of aortic valve replacement (AVR).OBJECTIVE To provide new insights into the natural history of outpatients with native AS based on a large regionwide population study with inclusion by all cardiologists regardless of their mode of practice. DESIGN, SETTING, AND PARTICIPANTSBetween May 2016 and December 2017, consecutive outpatients with mild (peak aortic velocity, 2.5-2.9 m/s), moderate (peak aortic velocity, 3-3.9 m/s), and severe (peak aortic velocity, Ն4 m/s) native AS graded by echocardiography were included by 117 cardiologists from the Nord-Pas-de-Calais region in France. Analysis took place between August and November 2020.MAIN OUTCOMES AND MEASURES Natural history, need for AVR, and survival of patients with AS were followed up. Indications for AVR were based on current guideline recommendations. RESULTS Among 2703 patients (mean [SD] age, 76.0 [10.8] years; 1260 [46.6%] women), 233 (8.6%) were recruited in a university public hospital, 757 (28%) in nonuniversity public hospitals, and 1713 (63.4%) by cardiologists working in private practice. A total of 1154 patients (42.7%) had mild, 1122 (41.5%) had moderate, and 427 (15.8%) had severe AS. During a median (interquartile range) of 2.1 (1.4-2.7) years, 634 patients underwent AVR and 448 died prior to AVR. Most deaths were cardiovascular (200 [44.7%]), mainly associated with congestive heart failure (101 [22.6%]) or sudden death (60 [13.4%]). Deaths were noncardiovascular in 186 patients (41.5%) and from unknown causes in 62 patients (13.8%). Compared with patients with mild AS, there was increased cardiovascular mortality in those with moderate (hazard ratio, 1.47 [95% CI, 1.07-2.02]) and severe (hazard ratio, 3.66 [95% CI, 2.52-5.31]) AS. The differences remained significant when adjusted for baseline characteristics or in time-dependent analyses considering AS progression. In asymptomatic patients, moderate and mild AS were associated with similar cardiovascular mortality (hazard ratio, 0.99 [95% CI, 0.44-2.21]). CONCLUSIONS AND RELEVANCEWhile patients in this study with moderate AS had a slightly higher risk of cardiovascular death than patients with mild AS, this risk was much lower than that observed in patients with severe AS. Moreover, in asymptomatic patients, moderate and mild AS were associated with similar cardiovascular mortality.

The threshold for activation of the humoral renal antihypertensive system, presumably residing in the renomedullary interstitial cells (RIC), is substantially reset upwards in the spontaneously hypertensive rat (SHR). Depressor reactions, normally elicited by an increased renal perfusion pressure, can be inhibited either by high frequency renal nerve stimulation or blockade of nitric oxide synthesis, i.e. manoeuvres decreasing renal blood flow at this high perfusion pressure. The present study was designed to explore the effects on regional renal haemodynamics of blocking NO synthesis with N-omega-nitro-L-arginine (L-NNA) in chloralose anaesthetized SHR and Wistar rats. Mean arterial blood pressure (MAP), heart rate (HR), renal blood flow (RBF), cortical blood perfusion (CBP) and papillary blood perfusion (PBP) were measured in renally innervated and denervated SHR (Si n = 8, Sd n = 8) and in Wistar rats (Wi n = 10, Wd n = 10). An innervated non-treated Wistar group served as control (Ci n = 12). The laser Doppler technique was used to record CBP and PBP. MAP increased in all groups receiving L-NNA while HR, RBF and CBP simultaneously decreased. The relative decreases in RBF were more marked into the two SHR groups than in the corresponding Wistar groups. After L-NNA PBP also decreased in all four groups despite the increased MAP and more so in the Si group; Wi -19 +/- 8 (P < 0.05), Wd -17 +/- 6 (P = 0.07), Si -50 +/- 9 (P < 0.01) and Sd -25 +/- 9% (P < 0.05). We conclude that NO is important for maintaining PBP especially in SHR. The more marked decrease in PBP in the innervated SHR suggests a NO/renal nerve interaction in the control of renomedullary blood flow in SHR. This finding may be of importance for the regulation of the humoral renal depressor mechanism.

Although most patients with stable CAD are receiving evidence-based medications according to guidelines, there remain subgroups at higher risk of non-optimal treatment. In particular, it might be feasible to improve prevention by focusing on patients in whom a long time has elapsed since the last coronary event.